Can I DISABLE the portfolio function? I just want to combine 2 .pdfs, not create a portfolio

I dont know how and when acrobat decides to create a portfolio versus just combining 2 or more .pdfs in the "normal" way, but I dont really want or need the portfolio function and it seems to just be slow, clunky and cause my acrobat to crash more than it does help.

When I want to combine, for example, two .pdfs with 3 pages each, I just want adobe to combine them into one 6 page .pdf, not create a portfolio w/ the 2 separate .pdfs. I notice this problem the most using the plug-in for Outlook. I select one or more emails and want to create one .pdf containing all those emails. Sometimes that's exactly what adobe does. Other times for whatever reason it decides to create a portfolio and put all the separate emails in it as separate .pdf files. As I mentioned it then tends to crash on me when I attempt to navigage it. And yes I'm using the most recent patch.

When and how does acrobat decide whether to simply combine .pdfs into one vs. creating a portfolio, and it is possible for me to just disable the portfolio function?